In operation, when an elevator cab stops at a certain floor, the interior door of the elevator cab (“cab door”) and exterior door of the floor (“hoistway door”) must meet and slide open and closed uniformly. To accomplish this, the doors slide along a bottom sill that has horizontal grooves to guide the door movement. There is a portion of the sill that is constructed in the cab (“cab sill”) and a portion of the sill that is constructed on the floor where the cab stops (“hoistway sill.”) Jointly, the cab sill and hoistway sill are known as an “elevator sill system.” When the cab stops at a given floor, the cab sill and the hoistway sill align allowing for uniformity in the opening and closing of the cab and hoistway doors.
Cab and hoistway sills are utilized in elevator systems that have sliding doors. Both sills are comprised of a sill foundation material with a sill surface material. Cab and hoistway sills have horizontal grooves. A set of door gibs (guides) attach to the bottom of a cab door and/or hoistway door and travels in the horizontal grooves of a cab and/or hoistway sill. This configuration allows the corresponding cab door and hoistway door to open and close uniformly. The cab and hoistway sill materials typically undergo significant wear and tear, as well as stress from the continual opening and closing of the cab and/or hoistway doors and foot traffic. In addition, cab and hoistway sills must be fireproof, fire resistant and/or fire rated to ensure that during a fire emergency, smoke and fire stay contained to the affected floor of a multistory building. Sill materials must be able to withstand fire and smoke stresses and create an acceptable barrier over an acceptable time frame.
Typically, existing elevator sill systems comprise a unified sill foundation material and a sill surface material, i.e., they are one continuous material fabricated as one piece. As such, cab and hoistway sills are constructed from durable and fireproof materials, typically, cast or extruded aluminum, bronze, iron, stainless steel or nickel silver. Softer materials, such as aluminum, or plastics and other manufactured materials such as PVC, acrylic, polycarbonate, ABS, polystyrene, epoxy, resin, epoxy resin and the like are easier, faster and less expensive to manufacture, but wear much faster. These softer materials can also provide for fireproofing. On the other hand, harder and more durable materials, such as cast or extruded bronze, iron, stainless steel, or nickel silver and other architecturally desirable metals, are difficult and more expensive to manufacture, but when made and installed properly, last longer and remain cosmetically more attractive. Extruded stainless steel and other materials have the additional limitation in that the extrusion process does not provide for sharp edges and angles, i.e., what is required to produce cosmetically and/or architecturally desirable visible surfaces and/or treads. This limitation is present in other extruded metals, thus making extruded elevator sill systems aesthetically and architecturally disfavored. Due to this limitation, aesthetically desirable cab and hoistway sills are fabricated from several different non-extruded sections that must be welded together—an expensive and time consuming process.
In many circumstances and for a variety of reasons, including but not limited to brand competition and varying architectural limitations, there are no standard unified dimensions of a cab and/or hoistway sill. This substantially raises the costs and time necessary for construction of cab and hoistway sills.
Recently, there have been attempts at improving currently available elevator sills and hoistway sills. For example, American Safety Tread Co., Inc. has developed a cast anti slip protection sill. They manufacture an “‘alumacast’—corrosion resistant, maintenance free aluminum alloy all-purpose usage; ‘feracast’—cast iron all-purpose usage. Will withstand heavy industrial punishment. Ships with one coat of shop applied black paint; “bronzacast/nickelcast’—natural bronze finish makes this an ideal choice for an upscale, classic effect.” See www.americansafetytread.com/cast/elevator-door-sills/.
In another example, U.S. Pat. No. 5,609,224 titled, “ELEVATOR DOOR SILL” issued Mar. 11, 1997 discloses, “an elevator cab (10) with a door sill (28) adjacent to the landing sill (40) with a gap (44) there between and door sill and/or landing sill configured to produce a visual effect of enlarging the visual appearance of the gap.”
In another example, U.S. Pat. No. 5,715,913 titled, “DOOR SILL FOR AN ELEVATOR CAR” issued Feb. 10, 1998 discloses a “sill system for an elevator car, comprising a sill profile (5), a lower door guide (7) movable in a slot (12) in the sill profile (5) and a guide holding bracket (9) for connecting the lower door guide (7) to the door. The guide holding bracket (9) is passed to the lower door guide (7) from below the surface level of the car floor (3).”
In another example, U.S. Pat. No. 6,684,573 titled, “ELEVATOR DOOR SILL ASSEMBLY” issued Feb. 3, 2004 discloses an “elevator door sill assembly for use in elevator systems that have sliding doors. The door sill assembly comprises a sill plate, a support sill located below the sill plate having a rail that presents an inboard sliding surface and an outboard sliding surface. The assembly also comprises a first guiding surface that engages that inboard sliding surface and a second guiding surface that engages the outboard sliding surface. The assembly prevents that bottom of the elevator door from swinging while the door slides opened and closed. The sill assembly and guide system may be used with either hoistway doors or elevator car doors.”
In another example, U.S. Pat. No. 6,938,380 titled, “ELEVATOR ENTRANCE SILL STRUCTURE AND INSTALLATION METHOD” issued Sep. 6, 2005 discloses an invention that “related to a cost saving way of solving a difficult problem in the structure and installation and leveling of an elevator sill. This invention provides ease of installing from the hallway without the use of a moving elevator platform. The structure consists of a sill, a cradle for the sill and a pair of end brackets for supporting the cradle. The pair of spaced L-shaped end brackets are provided for attachment to the hall floor. A vertically adjustable sill is mounted on the sill cradle. The elevator door sill cradle is adjustable vertically by means of fasteners that are moveable in vertical slots in the end brackets and is horizontally adjustable on the cradle by means of fasteners that are moveable in horizontal slots provided in the cradle.”
In another example, Application No. PCT/US2009/068633 discloses, “an exemplary sill for use in an elevator system includes a sill plate that is a single piece of metal. The sill plate has a first portion in a first plane and a second portion adjacent to the first portion. The second portion is bent into a second plane that intersects the first plane. A third portion is adjacent to the second portion. The third portion is bent at least partially into a third plane that intersects the second plane. A fourth portion is adjacent to the third portion. The fourth portion is bent into a fourth plane that intersects the third plane and intersects the first plane. A fifth portion is adjacent to the fourth portion. The fifth portion is bent into the first plane. The second, third and fourth portions collectively establish a groove that is configured to receive a portion of an elevator system door. A base portion is provided in a plane parallel to the first plane. Connector portions near opposite ends of the base portion protrude from the base portion in a direction toward the first plane of the sill plate. At least one of the connector portions is connected to a selected portion of the sill plate near an end of the sill plate.”
There is no currently disclosed cab and/or hoistway sill or elevator sill system that combines the low cost and ease of manufacturing of sills comprised of inexpensive materials and the high durability, fire rating and attractive finish of expensive custom fabricated architecturally desirable nonferrous materials such as bronze, stainless steel, nickel silver or other architecturally desirable ferrous materials. Objectives of the present invention include providing a low cost, easy to manufacture, durable, fire rated, attractive and fully customizable cab and/or hoistway sill that includes sharp, architecturally and aesthetically desirable angled, non-rounded edges. All known elevator cab and hoistway sills sacrifice one or more of the foregoing attributes. The present invention provides a solution to the unmet need by providing cab and hoistway sills that are economical to manufacture that are also highly durable, fire rated, possesses an architecturally attractive and safety conscious finish consisting of architecturally and aesthetically desirable materials and custom designed surface finishes, as well as sharp, angled non-rounded edges.
The present invention also allows for existing elevator sill systems to be upgraded by cladding with sill foundation coverings consisting of architecturally and aesthetically desirable materials, thus eliminating the costly and destructive exercise of removing and replacing preexisting cab and hoistway sills when a new sill is needed or desired.
None of the foregoing references, alone or in combination, teach the salient and essential features of the instant invention. There remains, therefore an unmet need for a device that provides all of the attributes of a low cost, economical to manufacture, durable, fire rated, attractive and fully customizable cab sill and hoistway sill.